Valve shim - Now a miss

[HUS457]

Hey Everyone. As the title says, I shimmed my valves but now i have a miss. I checked the valve clearances after I shimmed & they're in spec. Its not the intake air sensor, engine or chassis ground. It seems to be timed right & the plugs/coils were in tight. The miss seems to be on deceleration, or if I try to hold a cruising rpm. It seems to get worse the higher the rpm. Mind you this is in my garage with no drive belt so maybe no back pressure? Any ideas on what to check? Tx

 

[captainruss99]

Can you throw the belt on it and run it? I have noticed on previous sleds that without the load, and at higher than usual rpms, they sometimes act strange. I was chasing a ghost one time for many hours, a buddy stopped by my garage, said to put the belt on, and it would sound normal. And it did. I wasted all that time for nothing.

 

[HUS457]

Tx captainruss99, I checked again & 3 of my exhaust valves are between 10-11 thou. So I’m thinking that’s my miss. I got a buddy giving me a hand but he’s skeptical 1/2 a thou loose on 3 exhaust valves would cause the miss. We’ll find out I guess.

 

[HUS457]

Lesson learned. I previously relocated the fuse block to the top of the belt guard. Part of the loom was contacting the frame that the guard attached to. After 5000k it managed to chafe through the loom and started to arc on a wire. Easy fix but heads up to anyone else who did the fuse block relocation on the belt guard.

So the miss was unrelated to the shimming.

 

[HUS457]

Hey, 800k on the sled since shimming. Can confirm, shimming made little to no difference on my hard starts. My sled is a 2015 S-TX with 12,500k when I shimmed it. I didn’t have kick backs like some, and until this year I didn’t have any backfiring.
My hard starts are simply, the sled will not start. I always use the same starting procedure;

Turn the key on & let the fuel pump prime
Then turn the key over to start
I don’t hold the key longer then 2 seconds
Usually the sled starts before 2s.

So a hard start for me is simply, the sled doesn’t start in the 2 seconds. I have held the key on longer to see if it makes a difference. It doesn’t. If it doesn’t start within 2 seconds of holding the key, it isn’t going to start on that key cycle. So, I turn the key off & wait for the display to go out. Then repeate the above process. Sometimes it takes 3 attempts. There is some occasions when I can turn the key off & back on quickly and that sometimes works. Almost depending on which stroke a cylinder is on or something, not sure. Like bumping it.

I did have 2 backfires this year. Happened on the 1st start of the day on a cold am & mid ride amongst a bunch of Polaris’s. I had enough once that happened which led to the shimming. No backfires since shimming, but it’s only been 800k.

What has shown a reduction in hard starts was removing the goggle bag from the dash & letting the heat out. A friend of mine who’s been wrenching on Yamaha’s for decades pointed that out. I’ve had 1 ride that was a little over 400k on that experiment which seemed to drop the amount of hard starts noticeably. But with only 400k I can’t say that’s not coincidental. But I usually find I need about 80k on the sled before the hard starts begin to happen. So possibly heat related? But also, there’s lots of Vipers out there running screens instead of goggle bags that get hard starts who knows.

Figured I’d update the group on my results.

Update April 2nd, 23 - After another 270k, removing the google bag deffinitly seems to have reduced the frequency of the hard starts.

Tx

 

[Phazer2Viper]

Hey, 800k on the sled since shimming. Can confirm, shimming made little to no difference on my hard starts. My sled is a 2015 S-TX with 12,500k when I shimmed it. I didn’t have kick backs like some, and until this year I didn’t have any backfiring.
My hard starts are simply, the sled will not start. I always use the same starting procedure;

Turn the key on & let the fuel pump prime
Then turn the key over to start
I don’t hold the key longer then 2 seconds
Usually the sled starts before 2s.

So a hard start for me is simply, the sled doesn’t start in the 2 seconds. I have held the key on longer to see if it makes a difference. It doesn’t. If it doesn’t start within 2 seconds of holding the key, it isn’t going to start on that key cycle. So, I turn the key off & wait for the display to go out. Then repeate the above process. Sometimes it takes 3 attempts. There is some occasions when I can turn the key off & back on quickly and that sometimes works. Almost depending on which stroke a cylinder is on or something, not sure. Like bumping it.

I did have 2 backfires this year. Happened on the 1st start of the day on a cold am & mid ride amongst a bunch of Polaris’s. I had enough once that happened which led to the shimming. No backfires since shimming, but it’s only been 800k.

What has shown a reduction in hard starts was removing the goggle bag from the dash & letting the heat out. A friend of mine who’s been wrenching on Yamaha’s for decades pointed that out. I’ve had 1 ride that was a little over 400k on that experiment which seemed to drop the amount of hard starts noticeably. But with only 400k I can’t say that’s not coincidental. But I usually find I need about 80k on the sled before the hard starts begin to happen. So possibly heat related? But also, there’s lots of Vipers out there running screens instead of goggle bags that get hard starts who knows.

Figured I’d update the group on my results.

Update April 2nd, 23 - After another 270k, removing the google bag deffinitly seems to have reduced the frequency of the hard starts.

Tx

Interesting that the heat could be a factor. I am going to try removing the bag and see what happens. I am having hard starts too. 16,000 miles on my machine and 7,000 since the 1st valve adjustment. The symptoms this time are slightly different than when it was due to the valve clearance. I am wondering if it could be my fuel injectors. i have run across a couple different people on here that had to change them out.

 

[HUS457]

Interesting that the heat could be a factor. I am going to try removing the bag and see what happens. I am having hard starts too. 16,000 miles on my machine and 7,000 since the 1st valve adjustment. The symptoms this time are slightly different than when it was due to the valve clearance. I am wondering if it could be my fuel injectors. i have run across a couple different people on here that had to change them out.

Maybe try a can of seafoam & see if that makes a difference? Have you ever replaced your fuel filter?

Although I would think that things like a fuel filter or injectors would give you symptoms consistently, not just when starting. But, cheap things to try to see if it makes a difference.

When I bought my Viper it had been sitting for over a year with non stabilized gas. Battery was left hooked up too and had gone bad. So it was hard to start. I dumped the old gas, replaced the fuel filter, replaced the battery, filled with fresh gas & seafoam and it was like a new machine.

Maybe try a few little things first in hopes you wont have to do the larger job for a few thousand more klms lol.

But I hate those goggle bags. I bought an new Sidewinder & it came with one. Every time I started it after stopping for a few mins it would run rough. Brand new machine so it wasn't likely anything mechanical. Almost like the heat was boiling the gas in the throttle bodies, fuel line & filter. Once that gas was burned off it was fine. I tossed that bag pretty quick and ordered the plastic louvre panel that comes with the SE which greatly improved the issue. Not 100% but very close. Still get the odd troubled start or single miss. I attribute this to a characteristic of the sleds. The hood holds alot of heat.